The benefits of regular aerobic exercise are well established. However, due to time constraints, inclement weather, and other reasons, many people are prevented from aerobic activities such as walking, jogging, running, and swimming. In response, a variety of exercise equipment has been developed for aerobic activity. It is generally desirable to exercise a large number of different muscles over a significantly large range of motion so as to provide for balanced physical development, to maximize muscle length and flexibility, and to achieve optimum levels of aerobic exercise. It is further advantageous for exercise equipment to provide smooth and natural motion, thus avoiding significant jarring and straining that can damage both muscles and joints.
While various exercise systems are known in the prior art, these systems suffer from a variety of shortcomings that limit their benefits and/or include unnecessary risks and undesirable features. For example, stationary bicycles are a popular exercise system in the prior art; however, these machines employ a sitting position that utilizes only a relatively small number of muscles, through a fairly limited range of motion. Cross-country skiing devices are also utilized to simulate the gliding motion of cross-country skiing. While cross-country skiing devices exercise more muscles than stationary bicycles, the substantially flat shuffling foot motion provided by the ski devices limits the range of motion of some of the muscles being exercised. Another type of exercise device simulates stair climbing. These devices exercise more muscles than stationary bicycles; however, the rather limited range of up-and-down motion utilized does not exercise the user's leg muscles through a large range of motion. Treadmills are still a further type of exercise device in the prior art. Treadmills allow natural walking or jogging motions in a relatively limited area. A drawback of the treadmill, however, is that significant jarring of the hip, knee, ankle and other joints of the body may occur through use of this device.
A further limitation of a majority of exercise systems in the prior art lies in the limits in the types of motions that they can produce. Relatively new classes of exercise devices are capable of producing elliptical motion. Exercise systems create elliptical motion, as referred to herein, when the path traveled by a user's feet while using the exercise system follows an arcuate or ellipse-shaped path of travel. Elliptical motion is much more natural and analogous to running, jogging, walking, etc., than the linear-type, back and forth motions produced by some prior art exercise equipment.
Exercise devices that can provide arm and shoulder motions as well as arcuate foot motions are also desirable. Prior art devices utilize arm and shoulder motions that are linked to foot motions. These linked devices incorporate forced coordinated motion, where the motions of a user's feet are linked to the motions of a user's arms and shoulders. Thus, the user's feet are forced to move in response to the movement of the user's arms and shoulders (in substantially an equal and opposite amount), and vice versa.
One drawback to these linked devices lies in the ability of the user during operation to unintentionally exert little or no force on the arm apparatuses due to the linkage with the foot links. The arm apparatus travels through a given path regardless of whether the user is exerting any force on the arm due to the force being exerted on the foot links. The opposite drawback can also occur where too much force is being exerted on the arm apparatus, thereby diminishing the amount of force required to be exerted on the foot apparatuses. a corollary drawback is the inability to place a different resistive load on the arm apparatus than on the foot links or to vary the load placed on the arm links relative to the load placed on the foot links.
A further drawback is that, in existing machines the arm links travel a full stroke length, in conjunction with the foot links. This can lead to arm movements that are not consistent with the natural movement of the arms, particularly when a user operates the machine at a rapid pace. Also, a person with shorter arms may desire a different arm stroke length than a taller person.
In addition, in the prior art devices where the arm and shoulder motions that are linked to foot motions, the given path through which the arm travels follows a generally convex movement relative to the ground where the forward-most and rearward-most positions of the handles are lower than the mid-travel position of the handle. This generally convex motion is in contrast to the natural motion of the arms during running, which follow a generally concave motion relative to the ground.
What would thus be desirable is an exercise device that provides for smooth natural action, exercises a relatively large number of muscles through a large range of elliptical motion, employs arm, shoulder, and rotational movement, and provides for safety and stability. Such an exercise device would assure that the user exerts a proper or desired amount of arm and shoulder force. Such an exercise device would allow a user to place and vary a different resistive load on the arm apparatus than on the foot links. Such an exercise device would provide a more natural path for the arms. Such an exercise device would provide a full body elliptical exercise experience that allowed for a user to define, and vary as desired, the stroke length of the arm links.